Such a potential problem could be flickery or jerky animations. Since the duration of the animation on normal use can be pretty short, it may be difficult to see what's going on. Using the "Toggle Slow Animations" option, the first under the "Debug" menu, slows it down enough to allow getting an insight on what may be the problem. For an example of such problem, and the difference that slower animations makes, see the video below:
Another group of debugging functionality has the "Color Blended Layers", "Color Copied Images", "Color Misaligned Images" and "Color Offscreen-Rendered" options. All these options can be used to expose inefficient composite drawing, and they're also available through Instruments.
Yet another group of functionality appears under the "Location", which allows simulating changing the location for apps that use location services.
I'm amazed by the quality of development tools that Apple provides, far exceeding other platforms.
If you have an app developed, perhaps by an outsourcing developer like me, and notice some problems with animation, you may ask your developer to toggle those options and produce a screen recording of the app running in the simulator, like I did above, to prove that any issues have been addressed.